In a wireless communication, the function of RF front end module is to receive RF signal and convert the RF signal into signal of medium frequency so as to be further processed by the circuit at the back end. Here the conversion of RF frequency signal into medium frequency signal is completed by the RF front end processor chip.
FIG. 1 is an illustration of the prior art RF front end module. The RF front end module 10 comprising of an antenna 12, a filter 14, an adapter 16, a RF front end processor chip 18 and a resonant signal generator 20. Antenna 12 is used to receive RF signal and RF signal of different frequencies are received through the design in the antenna structure. Filter 14 is used to receive RF signal in order to generate a RF filtered frequency. What needs to be noticed is, in order to reduce manufacturing cost and for the convenience concern, antenna 12 is thus designed toward the direction of multiple frequencies and filter 14 is used to filter out RF signals so as to generate RF filtered signals which are used in special frequency sections and to be further processed by circuits after RF front end module 10. Adapter 16 is used to receive RF filtered signal so as to convert it into double balance architecture S1 and S2 and RF front end processor chip 18, through the reception of signals S1 and S2 and a resonant signal generated by resonant signal generator 20, is used to generate medium frequency signal SIF to be further processed and used by the circuit after RF front end module 10. Wherein, adapter 16 is realized through transform form and resonant signal generator 20 can be realized through quartz oscillator.
RF front end processor chip 18 comprising of a low noise amplifier 182 and a frequency mixer184 (Mixer), low noise amplifier 182 (LNA) is used to receive signals S1 and S2 so as to reduce the noises of S1 and S2 and to amplify signals S1 and S2. Frequency mixer 184 is used to receive the output signal of low noise amplifier 182 and the above-mentioned resonant signal so as to generate medium frequency SIF. Generally speaking, since frequency mixer 184 adopts a design of double-balance structure and in order to cope with such structure, low noise amplifier 182 has to be realized in the form of differential amplifier circuit; therefore, the circuit structure is very complicated and the power loss is very large and moreover, the noise index is also very high.
Hence, a RF front end processor chip circuit structure that can reduce power loss and noise index is expected.